在学习 OpenGL ES 的工作原理时，我试图让一个带纹理的正方形出现在我的屏幕上。这是广场的相关代码。该代码基于谷歌示例：
public class Shape2Square {
private static final String TAG = "Shape2Square";
private final String vertexShaderCode =
"uniform mat4 uMVPMatrix;" +
"attribute vec4 vPosition;" +
"attribute vec2 a_TexCoordinate;"+
"varying vec2 v_TexCoordinate;"+
"void main() {" +
"v_TexCoordinate = a_TexCoordinate;"+
"gl_Position = uMVPMatrix * vPosition;" +
"}";
private final String fragmentShaderCode =
"precision mediump float;" +
"uniform sampler2D u_Texture"+
"varying vec2 v_TexCoordinate;"+
"void main() {" +
"gl_FragColor = texture2D(u_Texture, v_TexCoordinate);"+
"}";
private final FloatBuffer vertexBuffer;
private final FloatBuffer textureBuffer;
private final ShortBuffer drawListBuffer;
private final int mProgram;
private int mPositionHandle;
private int mMVPMatrixHandle;
private int mtexture;
private int mtexCoordHandler;
private int mtextureHandler;
// number of coordinates per vertex in this array
static final int COORDS_PER_VERTEX = 3;
static float squareCoords[] = { -0.3f, -0.3f, 0.0f, // top left
-0.3f, 0.3f, 0.0f, // bottom left
0.3f, 0.3f, 0.0f, // bottom right
0.3f, -0.3f, 0.0f }; // top right
// u,v
static float texturedata[] = {0.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
1.0f, 0.0f};
private final short drawOrder[] = { 0, 1, 2, 0, 2, 3 };
private final int vertexStride = COORDS_PER_VERTEX * 4;
public Shape2Square() {
// initialize vertex byte buffer for shape coordinates
ByteBuffer bb = ByteBuffer.allocateDirect(squareCoords.length * 4);
bb.order(ByteOrder.nativeOrder());
vertexBuffer = bb.asFloatBuffer();
vertexBuffer.put(squareCoords);
vertexBuffer.position(0);
ByteBuffer bbtexture = ByteBuffer.allocateDirect(texturedata.length*4);
bbtexture.order(ByteOrder.nativeOrder());
textureBuffer = bbtexture.asFloatBuffer();
textureBuffer.put(texturedata);
textureBuffer.position(0);
ByteBuffer dlb = ByteBuffer.allocateDirect(drawOrder.length * 2);
dlb.order(ByteOrder.nativeOrder());
drawListBuffer = dlb.asShortBuffer();
drawListBuffer.put(drawOrder);
drawListBuffer.position(0);
int vertexShader = CommonMethods.loadShader(GLES20.GL_VERTEX_SHADER,
vertexShaderCode);
int fragmentShader = CommonMethods.loadShader(GLES20.GL_FRAGMENT_SHADER,
fragmentShaderCode);
mProgram = GLES20.glCreateProgram();
Shape2Square.checkGlError("glCreateProgram");
GLES20.glAttachShader(mProgram, vertexShader);
Shape2Square.checkGlError("glAttachShader");
GLES20.glAttachShader(mProgram, fragmentShader);
Shape2Square.checkGlError("glAttachShader");
GLES20.glLinkProgram(mProgram);
Shape2Square.checkGlError("glLinkProgram");
}
我从 logcat 得到的麻烦指向这个正方形的“绘制”方法。请注意，CommonMethods.loadTexture只需将位图代码加载到 OPEN GL 中：
EDIT1：（在代码中添加了 checkGlErrors）
public void draw(float[] mvpMatrix, int textureid) {
GLES20.glUseProgram(mProgram);
Shape2Square.checkGlError("glUseProgram");
vertexBuffer.position(0);
mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
Shape2Square.checkGlError("glVertexAttribPointer");
GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);
Shape2Square.checkGlError("glVertexAttribPointer");
GLES20.glEnableVertexAttribArray(mPositionHandle);
Shape2Square.checkGlError("glEnableVertexAttribArray");
textureBuffer.position(0);
mtexCoordHandler = GLES20.glGetAttribLocation(mProgram,"a_TexCoordinate");
Shape2Square.checkGlError("glGetAttribLocation");
GLES20.glEnableVertexAttribArray(mtexCoordHandler);
Shape2Square.checkGlError("glEnableVertexAttribArray");
GLES20.glVertexAttribPointer(mtexCoordHandler, 2, GLES20.GL_FLOAT, false, 8, textureBuffer);
Shape2Square.checkGlError("glVertexAttribPointer");
mtextureHandler = GLES20.glGetUniformLocation(mProgram, "u_Texture");
Shape2Square.checkGlError("mtextureHandler");
mtexture = CommonMethods.loadTexture(textureid);
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
Shape2Square.checkGlError("glActiveTexture");
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mtexture);
Shape2Square.checkGlError("glBindTexture");
GLES20.glUniform1i(mtextureHandler, 0);
Shape2Square.checkGlError("glUniform1i");
mMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
Shape2Square.checkGlError("glGetUniformLocation");
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mvpMatrix, 0);
Shape2Square.checkGlError("glUniformMatrix4fv");
GLES20.glDrawElements(GLES20.GL_TRIANGLES, drawOrder.length,
GLES20.GL_UNSIGNED_SHORT, drawListBuffer);
Shape2Square.checkGlError("glDrawElements");
GLES20.glDisableVertexAttribArray(mPositionHandle);
Shape2Square.checkGlError("glDisableVertexAttribArray");
}
public static void checkGlError(String glOperation) {
int error;
while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
Log.e(TAG, glOperation + ": glError " + error);
throw new RuntimeException(glOperation + ": glError " + error);
}
}
这样做会导致错误并强制应用程序关闭。logcat 导致glGetUniformLocation最可能的罪魁祸首是mMVPMatrixHandle在弄乱代码之后，这很奇怪，因为它以前工作过。为了证明我的观点，如果我删除所有纹理代码并添加一个具有所有通常相关性的 vColor（在实际代码和 fragmentShadercode 中），那么我将得到彩色方块。我不明白错误所在glGetUniformLocation或如何解决它，因此感谢您的帮助。
EDIT1：所以我试图清除“glgetuniformlocation”的checkglerror，但这令人失望，因为现在错误以“glUniformMatrix4fv”的形式出现。有什么大错特错...
EDIT2：决定在整个代码中使用 checkglerror，到目前为止，似乎整个绘制方法（包括 glUseProgram）都有错误。在绘制方法（包括附加着色器和链接）之前发生的 gl 位是可以的，没有错误。